M, n.
1. Print. A quadrat, the face or top of which is a perfect square; also, the size of such a square in any given size of type, used as the unit of measurement for that type: 500 m's of pica would be a piece of matter whose length and breadth in pica m's multiplied together produce that number. [Written also em.]
2. law A brand or stigma, having the shape of an M, formerly impressed on one convicted of manslaughter and admitted to the benefit of clergy.
M roof Arch., a kind of roof formed by the junction of two common roofs with a valley between them, so that the section resembles the letter M.
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Em n. Print. The portion of a line formerly occupied by the letter m, then a square type, used as a unit by which to measure the amount of printed matter on a page; the square of the body of a type.
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em
n 1: the square of a body of any size of type [syn: mutton, mut]
2: a linear unit (1/6 inch) used in printing [syn: pica em, pica]